CD32 is enriched on CD4(dim)CD8(bright) T cells

CD4(dim)CD8(bright) T cells, a genuine population of CD8(+) T cells, are highly activated and cytolytic. Recently, the low affinity IgG Fc fragment receptor CD32a was described as marker of HIV latency while others reported that CD32a is associated with T cell activation. Given that we have previously established that CD4(dim)CD8(bright) T cells are highly activated, mediate anti-HIV responses, and are infected by HIV, we assessed here CD32 expression on CD4(dim)CD8(bright) T cells in context of HIV. CD32 frequency on peripheral CD4(dim)CD8(bright) and CD4(+) T cells was determined by flow cytometry among HIV negative and HIV positive patients. We report that among HIV(-) individuals, mean CD32 percent expression was 60% on CD4(dim)CD8(bright) T cells and 17% on CD4(+) T cells (p<0.01). Among HIV(+) patients, mean CD32 percent expression was 54% on CD4(dim)CD8(bright) T cells and 12% on CD4(+) T cells (p<0.001). CD32 expression on CD4(dim)CD8(bright) T cells did not correlate with CD4 count and viral load and was not different by HIV serostatus. CD32 was also higher on other double positive T cell populations in both HIV negative and HIV positive donors in comparison to their single positive T cell counterpart. Together, these studies indicate that CD32 is enriched on double positive T cells regardless of HIV serostatus. The functional role of CD32 on these double positive T cells remains to be elucidated.